The present invention relates to a photoradiator for effectively radiating light propagating therethrough in a desired direction and in a desired quantity to the ambience, while furnishing it with an optical property suitable for a desired application.
Effective use of solar energy is the key to energy saving today and has been studied in various fields actively. For the most effective use of solar energy, solar energy has to be availed as it is without being transformed into another kind of energy such as thermal energy or electrical energy. In light of this, I have made various proposals for an illumination system which utilizes solar energy. The illumination system employs a light conducting element such as a fiber optic cable through which the sunlight converged by a lens or the like is conducted to a desired location to stream out thereat to illuminate the ambience.
In the illumination system of the type described, the light advancing through the light conductor has directivity. Therefore, if the light is output at a simple cut end of the light conductor, it becomes radiated over an angle .theta. which is usually as small as about 46.degree.. The light streaming through the simple cut end of the light conductor would fail to evenly illuminate a desired space such as a room. I have proposed in various forms a photoradiator which is designed to effectively diffuse light conducted by a fiber optic cable to provide even illumination over a wide range.
Another problem encountered with a light conducting element of the kind described is that when it is laid over a length sufficient for practical use, fringes develop in the light emanating from the light conductor which are undesirable for ordinary lighting applications, although some particular applications may rather prefer them. Where the light propagating through the light guide is a laser or the like, fringes appear therein even if the light conductor is of a very small diameter such as an optical fiber, rendering the light unfeasible for use with a laser microscope or the like.